GaAs and InGaAs Position-Controlled Quantum Dots Fabricated by Selective-Area Metalloorganic Vapor Phase Epitaxy

Abstract

Recent advances in micro- and nanofabrication techniques and/or crystal growth have made it possible to fabricate quantum functional devices with semiconductor quantum nanostructures such as quantum wires (QWRs) and quantum dots (QDs). In particular, the fabrication technique utilizing the nature of crystal growth is very promising, since it enables us to form highquality nanostructures free from process-induced damage and contamination in a relatively simple way. For example, self-assembled QDs (SAQDs) using the Stranski–Krastanow (SK) growth mode [1,2] have been shown to possess excellent optical properties reflecting their discrete density of states [3–8] and to realize various optoelectronic devices such as low-threshold, temperatureinsensitive laser diodes [9] and semiconductor optical amplifiers [10]. More recently, the atom-like properties of their electronic state were exemplified by the generation of single-photon emitters [11–14] as well as coherent spectroscopy [15–19].

Major and promising applications of QDs are also found in the field of electronics, such as single-electron tunneling (SET) transistors [20–22] and singleelectron (SE) memories [23–29]. In the former, a QD is used as a Coulomb island for the electron and QWRs are coupled to it through tunneling barriers.